Gas spring end members as well as gas spring and gas damper assemblies including same

ABSTRACT

A piston assembly including an integral piston chamber with an increased volume that is maximized by providing a mounting arrangement whereby the piston can be mounted to a structural member such that the piston chamber surrounds at least two sides of the structural member. A gas damping passage is disposed in fluid communication with the piston chamber and is dimensioned such that pressurized gas transferred through the gas damping passage can dissipate kinetic energy acting on the piston assembly. The piston chamber can therefore utilize space adjacent the structural member to which it is mounted thereby resulting in a piston chamber of a greater volume than prior art designs. A gas spring and gas damper assembly utilizing such a piston assembly is also included.

This application is a continuation-in-part of U.S. patent applicationSer. No. 13/993,551, filed on Jun. 12, 2013, now U.S. Pat. No.8,801,016, which was the National Stage of International Application No.PCT/US11/65811, filed Dec. 19, 2011 which claims the benefit of U.S.Provisional Application No. 61/425,144, filed Dec. 20, 2010, and whichclaims the benefit of U.S. Provisional Application No. 61/896,547, filedOct. 28, 2013, the contents of each of which is hereby incorporatedherein by reference in its entirety.

BACKGROUND

The subject matter of the present disclosure broadly relates to the artof fluid suspension systems. It finds particular application inconjunction with gas spring assemblies such as are commonly used invehicle suspension systems, and will be described herein with particularreference thereto. However, it is to be appreciated that the subjectmatter of the present disclosure is capable of broad use in a widevariety of applications and environments and that the specific referenceherein to use in vehicle suspension systems is merely exemplary.

Vehicle suspension systems typically include a plurality of springelements for accommodating forces and loads associated with theoperation and use of the vehicle. In such vehicle suspension systemapplications, it is often considered desirable to select spring elementsthat have the lowest suitable spring rate, as this favorably influencesride quality and comfort. That is, it is well understood in the art thatthe use of spring elements having higher spring rates (i.e., stiffersprings) will transmit a greater magnitude of road inputs into thesprung mass of the vehicle and that this typically results in a rougher,less-comfortable ride. Whereas, the use of spring elements having lowerspring rates (i.e., softer, more-compliant springs) will transmit alesser amount of the road inputs to the sprung mass and will, thus,provide a more comfortable ride.

With more specific reference to gas springs, it is possible to reducethe spring rate of gas springs, thereby improving ride comfort, byincreasing the volume of pressurized gas operatively associated with thegas spring. This is commonly done by placing an additional chamber,cavity or volume filled with pressurized gas into fluid communicationwith the primary spring chamber of the gas spring, as is well known bythose of skill in the art. Such additional volumes can be formed withina component of the gas spring itself, as shown, for example, in U.S.Pat. No. 5,954,316, or provided separately and connected through one ormore passages, as shown, for example, in U.S. Pat. No. 6,691,989.

While it is known to increase the volume of the pressurized gasassociated with the gas spring by providing external reservoirs orfluidly connecting a piston chamber with the main spring chamber, suchapproaches include certain disadvantages that may have limited theadoption and use thereof. For example, providing a remote reservoirgenerally involves mounting a separate reservoir and connecting it tothe main spring chamber via a hose or the like. This approach introducesadditional potential leak points, and requires additional steps in themanufacturing and/or assembly processes. Providing additional volume byconnecting the main spring chamber to a piston chamber can providesuitable results in some applications, but the additional volume thatcan be added is often limited by mounting constraints. For example, pastpiston designs generally include a planar mounting surface on the bottomof the piston for mounting the piston to a corresponding planar supportmember. Given the generally tight spaces in which such pistons are oftenmounted, the additional volume added to the spring chamber is oftenlimited to the volume of the piston chamber that is located above themounting surface.

Accordingly, it is believed desirable to develop a gas spring piston aswell as a gas spring assembly and vehicle suspension system that includesuch a gas spring piston that obviate the foregoing and/or otherdisadvantages of known constructions.

BRIEF DESCRIPTION

One example of a gas spring piston assembly in accordance with thesubject matter of the present disclosure can include an integral pistonchamber with an increased volume, such as by including a piston with amounting arrangement that permits the piston to be mounted on or alongan associated structural member such that the piston chamber surroundsat least two sides of the associated structural member. The pistonchamber can therefore utilize space adjacent (e.g., beside and/or below)the associated structural member to which the gas spring piston ismounted. As a result, an internal piston chamber having a greater volumethan conventional designs can be achieved.

One example of a gas spring assembly in accordance with the subjectmatter of the present disclosure can include an end member adapted to bemounted to a first associated support structure, a gas spring pistonassembly adapted to be mounted to a second associated support structurespaced from the first associated support structure, and a flexiblesleeve extending between and sealingly connected to the end member andthe gas spring piston assembly. The flexible sleeve can at leastpartially form a main chamber between the end member and the gas springpiston assembly for containing a pressurized gas. The piston assemblycan include a shell and a mounting surface. The shell can include apiston profile portion having an exterior surface over which theflexible sleeve is configured to roll. The shell can generally define apiston chamber for containing a pressurized gas. The mounting surfacecan be adapted for mounting the piston to the second associated supportstructure. The mounting surface can be recessed into the shell such thatthe piston chamber extends through a mounting plane of the pistondefined by the mounting surface. When the piston assembly is mounted onor along the second associated support structure, the piston chamber canat least partially surround the second associated support structure onat least two sides thereof.

In one example, the shell can include a generally cylindrical upperportion and a generally toroidal-shaped lower portion. The mountingsurface can be recessed into the toroidal lower portion of the shell.The toroidal lower portion can be configured to surround the mountingsurface such that the piston chamber can at least partially surround thesecond associated support structure by extending on or along at leastfour sides thereof when the piston assembly is mounted to the secondassociated support structure. The piston chamber can include an upperchamber portion and a lower reservoir extension. The reservoir extensioncan be configured to extend parallel to a linear edge of the secondmounting member. The recessed mounting surface can be located in aU-shaped recess in the shell.

In some cases the gas spring assembly can be part of a vehiclesuspension system. The vehicle suspension system can include first andsecond support structures that are disposed in spaced relation to oneanother. The gas spring assembly can be secured between the first andsecond support structures.

Another example of a gas spring assembly in accordance with the subjectmatter of the present disclosure can include an end member adapted to bemounted to a first associated support structure and a piston assemblyadapted to be mounted to a second associated support structure that isspaced from the first support structure. A flexible sleeve can extendbetween and sealingly connected to the end member and the pistonassembly, and thereby form a main chamber therebetween for containing apressurized gas. The piston assembly can include a shell having a pistonprofile portion that includes an exterior surface over which theflexible sleeve is configured to roll. The piston profile portion cangenerally define a piston chamber for containing a pressurized gas. Theshell can further include a reservoir portion that is rigidlyinterconnected with the piston chamber such that the interior volumes ofeach respective portion are in fluid communication with one another. Thepiston assembly can also include a mounting surface adapted for mountingthe piston assembly on or along the second support structure. Themounting surface can be recessed into the shell and can define amounting plane. The piston profile portion can extend in a firstdirection from the mounting plane and the reservoir portion can extendin a second direction from the mounting plane. As such, the pistonprofile portion can be located on a first side of the second supportstructure and the piston reservoir portion can be located on a secondside of the second support structure when the piston assembly is mountedon or along the second support structure.

In some cases, the reservoir portion can be generally U-shaped reservoirportion in cross-section. Additionally, in some cases, the mountingsurface can be located in the bottom of the U-shaped reservoir portionsuch that the piston reservoir straddles the support member when thepiston assembly is mounted on or along the support member. In othercases, the reservoir portion can have a shape corresponding to the shapeof the second support structure such that the reservoir surrounds thesecond support structure on or along at least two sides thereof when thepiston assembly is mounted on or along the second support structure. Insome cases, the piston chamber can include a generally cylindrical upperportion and the reservoir portion can have a generally toroidal shape.In some cases, the mounting surface can be recessed into the reservoirportion. In further cases, the reservoir portion can be configured tosurround an end of the second support structure such that the pistonchamber at least partially surrounds the second support structure on oralong at least four sides when the piston assembly is mounted on oralong the second support structure. Additionally, the shell can includea generally cylindrical upper portion and the reservoir portion can beconfigured to extend parallel to a linear edge of the second mountingmember. The mounting surface can be located in a U-shape recess in theshell.

A further example of a gas spring piston for a gas spring assembly caninclude a shell and a mounting surface. The shell can include a pistonprofile portion having an exterior surface over which an associatedflexible sleeve can be configured to roll. The shell can generallydefine a piston chamber for containing a pressurized gas. The mountingsurface can be adapted for mounting the piston to an associated supportmember. The mounting surface can be recessed into the shell such thatthe piston chamber extends through a mounting plane of the gas springpiston that is at least partially defined by the mounting surface. Insuch case, the piston chamber can at least partially surround theassociated support member on or along at least two sides thereof whenthe gas spring piston is mounted on or along the associated supportmember. Optionally, the piston chamber can include a generallycylindrical upper portion and a generally toroidal lower portion. Insome cases, the mounting surface can be recessed into the toroidal lowerportion of the piston chamber, and the toroidal lower portion can beconfigured to surround an end of the mounting surface. In such case, thepiston chamber can at least partially surround the associated supportmember on or along at least four sides thereof when the gas springpiston is mounted on or along the associated support structure.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic representation of one example of a vehicleincluding a suspension system and gas spring assemblies in accordancewith the subject matter of the present disclosure.

FIG. 2 is a side view of one example of a gas spring assembly inaccordance with the subject matter of the present disclosure.

FIG. 3 is a bottom perspective view of the gas spring piston assembly inFIG. 2.

FIG. 4 is a top plan view of the exemplary gas spring piston assemblyshown in FIGS. 2 and 3.

FIG. 5 is a cross-sectional side view of the exemplary gas spring pistonassembly in FIGS. 2-4 taken from along line 5-5 in FIG. 4.

FIG. 6 is a cross-sectional side view of the exemplary gas spring pistonassembly in FIGS. 2-5 taken from along line 6-6 in FIG. 4.

FIG. 7 is a cross-sectional side view of a portion of the exemplary gasspring piston assembly in FIGS. 2-6 taken from along line 7-7 in FIG. 4.

FIG. 8 is a top perspective view of another example of a gas springpiston assembly in accordance with the subject matter of the presentdisclosure.

FIG. 9 is a bottom perspective view of the exemplary gas spring pistonassembly in FIG. 8.

FIG. 10 is a top plan view of the exemplary gas spring piston assemblyin FIGS. 8 and 9.

FIG. 11 is a side elevation view of the exemplary gas spring pistonassembly in FIGS. 8-10.

FIG. 12 is a cross-sectional side view of the exemplary gas springpiston assembly in FIGS. 8-11 taken from along line 12-12 in FIG. 10.

FIG. 12A is a cross-sectional side view of the exemplary gas springpiston assembly in FIG. 12 shown including damping features suitable forforming a gas spring and gas damper assembly in accordance with thesubject matter of the present disclosure.

FIG. 13 is a top perspective view of a further example of a gas springpiston assembly in accordance with the subject matter of the presentdisclosure.

FIG. 14 is a bottom perspective view of the exemplary gas spring pistonassembly in FIG. 13.

FIG. 15 is a top plan view of the exemplary gas spring piston assemblyin FIGS. 13 and 14.

FIG. 16 is a side elevation view of the exemplary gas spring pistonassembly in FIGS. 13-15.

FIG. 17 is a cross-sectional side view of the exemplary gas springpiston assembly in FIGS. 13-16 taken from along line 17-17 in FIG. 15.

FIG. 18 is a graphical representation of one example of stiffness versusfrequency illustrating behavior of a gas spring and damper assembly thatincludes an elongated gas damping passage in accordance with the subjectmatter of the present disclosure.

FIG. 19 is a graphical representation of another example of stiffnessversus frequency illustrating behavior of a gas spring and damperassembly that includes two elongated gas damping passages in accordancewith the subject matter of the present disclosure tuned to providepressurized gas damping at two different target frequencies.

DETAILED DESCRIPTION

Turning now to the drawings, wherein the showings are for the purpose ofillustrating examples of the subject matter of the present disclosureand which are not intended as a limitation of the same, FIG. 1illustrates one example of a suspension system 100 disposed between asprung mass, such as an associated vehicle body BDY, for example, and anunsprung mass, such as an associated wheel WHL or an associatedwheel-engaging member or axle, for example, of an associated vehicleVHC. It will be appreciated that any such suspension system can includeany number of one or more systems, components and/or devices and thatthe same can be operatively connected between the sprung and unsprungmasses of the associated vehicle in any suitable manner. For example,such a suspension system can include a plurality of damping members (notshown), which can be operatively connected between the sprung andunsprung masses of the associated vehicle in any suitable manner.

Additionally, or in the alternative, such a suspension system caninclude a plurality of gas spring assemblies that are supported betweenthe sprung and unsprung masses of associated vehicle VHC. In theembodiment shown in FIG. 1, suspension system 100 includes six gasspring assemblies 102, 102′, one or more of which is disposed towardeach corner of the associated vehicle adjacent a corresponding wheel WHLthereof. However, it will be appreciated that any other suitable numberof gas spring assemblies 102, 102′ could alternately be used and thatsuch gas spring assemblies can be disposed in any other suitableconfiguration and/or arrangement. It will be recognized that gas springassemblies 102 are operatively associated with a front axle 104 ofvehicle VHC, while gas spring assemblies 102′ are operatively associatedwith respective rear axles 106 of vehicle VHC. As will be appreciated,gas spring assemblies 102 are shown as being mounted between axle 104and vehicle body BDY, whereas each of gas spring assemblies 102′ areshown as being mounted between respective trailing arms TRA and vehiclebody BDY.

Suspension system 100 can also optionally include a pressurized gassystem 120 that is operatively associated with the gas spring assembliesfor selectively supplying pressurized gas (e.g., air) thereto andselectively transferring pressurized gas therefrom. In the exemplaryembodiment shown in FIG. 1, pressurized gas system 120 includes apressurized gas source, such as a compressor 122, for example, forgenerating pressurized air or other gases. The gas supply system canalso include any number of one or more control devices of any suitabletype, kind and/or construction that may be capable of performing theselective transfer of pressurized gas. For example, a valve assembly 124is shown as being in communication with compressor 122 and can be of anysuitable configuration or arrangement. In the exemplary embodimentshown, valve assembly 124 includes a valve block 126 with a plurality ofvalves 128 supported thereon. Valve assembly 124 can also optionallyinclude a suitable exhaust, such as a muffler 130, for example, forventing pressurized gas from the system. Optionally, pressurized gassupply system 120 can also include a reservoir 132 in fluidcommunication with valve assembly 124 and suitable for storingpressurized gas.

The one or more control devices, such as valve assembly 124, forexample, can be in communication with gas spring assemblies 102 and 102′in any suitable manner, such as, for example, through suitable fluidtransmission lines 134. As such, pressurized gas can be selectivelytransmitted to and/or from the gas springs through valve assembly 124,such as to alter or maintain vehicle height at one or more corners ofthe vehicle, for example.

Suspension system 100 also includes a control system 136 that is capableof communication with any one or more other systems and/or components(not shown) of suspension system 100 and/or of VHC, and is capable ofselective operation and control of the suspension system. Control system136 includes a controller or electronic control unit (ECU) 138 incommunication with compressor 122 and/or valve assembly 124, such asthrough a suitable conductor or lead 140, for example, for selectiveoperation and control thereof, including supplying and exhaustingpressurized fluid to and from any number of one or more gas springassemblies, such as gas spring assemblies 102 and/or 102′, for example.Additionally, it will be appreciated that controller 138 can be of anysuitable type, kind and/or configuration.

Control system 136 can also optionally include one or more height ordistance sensing devices (not shown) as well as any other desiredsystems and/or components. Such height sensors, if provided, arepreferably capable of generating or otherwise outputting a signal havinga relation to a height or distance, such as between spaced components ofthe vehicle, for example. It will be appreciated that any such optionalheight sensors or any other distance-determining devices, if provided,can be of any suitable type, kind, construction and/or configuration,such as mechanical linkage sensors, ultrasonic wave sensors orelectromagnetic wave sensors, such as may operate using ultrasonic orelectromagnetic waves, for example.

Having described an example of a suspension system (e.g., suspensionsystem 100) that can include a gas spring assembly in accordance withthe subject matter of the present disclosure, one example of such a gasspring assembly will now be described in connection with FIGS. 2-7.Referring initially to FIG. 2, a gas spring assembly 200, such as may besuitable for use as gas spring assembly 102′ in FIG. 1, for example, isshown as including a first end member, such as top or bead plate 202,for example, and a second end member, such as piston assembly 204, forexample, that is spaced from the first end member. A flexible wall, suchas a flexible sleeve 206, for example, is secured between bead plate 202and piston assembly 204 and at least partially forms a spring chamber208 therebetween. Flexible sleeve 206 includes an upper mounting bead210 and a lower mounting bead 212 formed on opposing ends thereof.

Upper mounting bead 210 of the flexible sleeve 206 is captured by theperipheral edge of bead plate 202. The peripheral edge can be deformedaround the upper mounting bead in any manner suitable for forming asubstantially fluid-tight seal therewith. One or more securementdevices, such as mounting studs 214, for example, can be included alongbead plate 202. In the exemplary embodiment shown in FIG. 2, mountingstuds 214 project outwardly from the bead plate 202 and are securedthereon in a suitable manner. The one or more securement devices aresuitable for securing the bead plate 202 on an associated structuralcomponent or member ST1, such as a component of a vehicle, for example.A fluid communication port, such as a fluid passage 216, for example, isprovided to permit fluid communication with a spring chamber 208. In theexemplary embodiment shown, fluid passage 216 extends through at leastone of studs 214 and is in fluid communication with spring chamber 208.However, it will be appreciated that any other suitable fluidcommunication arrangement could alternately be used.

Although not illustrated in FIG. 2, the lower mounting bead of theflexible sleeve could be captured between an end closure and the pistonassembly in a conventional manner, and the end closure could be securedon the piston assembly using a suitable securement device or assembly,such as a mounting stud and nut, for example. Alternately, pistonassembly 204 could include a bead mounting wall 217 adapted to receiveand retain lower mounting bead 212, such as is shown in FIG. 2, forexample.

Piston assembly 204 includes piston chamber 218 defined at least in partby the interior volume of the piston assembly 204. A mounting surface220 is provided in a recess 224 for mounting piston assembly 204 to anassociated structural component or member ST2, which may be a trailingarm or axle tube, for example. A fastener, such as bolt 226, can beprovided for cooperating with a threaded bore 234 in mounting surface220 for securing piston assembly 204 on or along an associatedstructural component or member, such as, associated structural memberST2 having an elongated linear edge LE, for example. Of course, otherfastening arrangements could alternately be employed.

Turning to FIGS. 3-7, piston assembly 204 is shown in greater detail andis identified as including a shell 240 defining a piston profile portion244 and a reservoir portion 248. In this embodiment, reservoir portion248 has an at least partially toroidal shape and is also shown asincluding a pair of auxiliary reservoir extensions 252 protrudingtherefrom. Auxiliary reservoir extensions 252 are optional and can beconfigured to provide additional chamber volume as desired. The interiorsurface of shell 240 at least partially defines piston chamber 218 (seeFIG. 5), with the respective interior volumes of piston profile portion244 and reservoir portion 248 being rigidly interconnected. As used inthis description, terms such as “piston chamber” and the like refer tothe total volume of the interconnected regions defined within shell 240,which can include but are not limited to the volume within pistonprofile portion 244, the volume within reservoir portion 248, and otherinterconnected volumes (e.g., an auxiliary reservoir extension).

Piston profile portion 244 has an exterior surface over which flexiblesleeve 206 is configured to roll in conventional fashion when assembledas a gas spring assembly. Mounting surface 220 is provided in recess 224in shell 240 and defines a mounting plane MP (best seen in FIG. 6)through which at least a portion of piston chamber 218 extends. In otherwords, in this exemplary embodiment, the piston chamber extends aboveand below mounting surface 220. As will be appreciated, this featureallows piston chamber 218 to straddle the associated structuralcomponent (e.g., associated structural member ST2) when mounted thereto,thereby utilize space adjacent to the associated structural member forincreasing the volume of the piston chamber and enhancing theperformance of the gas spring assembly.

As will be appreciated, the overall shape of shell 240 is exemplary innature, and other shapes can be employed without departing from thescope of the disclosure. It will also be appreciated that shell 240 canbe a single unitary piece or can be made from two or more pieces joinedtogether, such as by welding, for example. Shell 240 can be formed fromany suitable material or combination of materials, such as plastic,steel, carbon fiber, etc.

As best shown in FIGS. 5-7, and especially FIG. 6, recess 224 isgenerally U-shaped in cross-section and is configured to receive astructural member, such as that illustrated in FIG. 2, for example. Suchstructural member may be associated with a trailing arm of a suspensionsystem, for example. When mounted to the structural component (e.g.,associated structural member ST2), reservoir portion 248 of pistonassembly 204 surrounds the associated structural member on at least twosides thereof. In this regard, piston chamber 218 surrounds the end ofassociated structural component ST2 on four sides (e.g., top, left,right and distal end), with only the bottom of the associated structuralmember not surrounded by a portion of the piston chamber. Of course,piston assembly 204 could be configured to completely surround theassociated structural member if desired or appropriate for a givenapplication. As will be appreciated, the shape of recess 224 can be anydesired shape. For example, the recess could be cylindrical for mountingalong a corresponding cylindrical structural member, such as an axletube or the like.

Turning now to FIGS. 8-12, another exemplary piston assembly 404 isillustrated that is suitable for use in forming a gas spring assembly,such as one of gas spring assemblies 102 and/or 102′, in FIG. 1, forexample. In this embodiment, piston assembly 404 includes a shell 440forming a piston profile portion 444 extending from a first side of abase plate 446, and includes a lower reservoir portion 448 in the formof a pair of spaced apart reservoir extensions 452 extending from asecond side of base plate 446. Reservoir extensions 452 and base plate446 together define a recess in the form of channel 426. A mountingsurface 420 is provided and includes a threaded bore 434 (FIG. 12)configured to receive a bolt (not shown in FIGS. 8-12) for securing thepiston assembly 404 to an associated structural component, such asassociated structural member ST2 in FIG. 2, for example, in a similarmanner to that previously disclosed in connection with FIG. 2. Inaddition to threaded bore 434 or, in the alternative thereto, bores 470can be provided through reservoir extensions 452 for passing fastenersfor further securing piston assembly 404 to an associated structuralcomponent (e.g., associated structural member ST2).

Reservoir extensions 452 are configured to straddle opposing sides of anassociated structural component when mounted thereto. Thus, unlike theembodiment of FIGS. 2-7 which is generally mounted to an end of astructural member, piston assembly 452 of the present embodiment can bemounted at a middle portion of a structural member (e.g., betweenrespective ends), or at an end thereof depending on the application. Asnoted, however, a wide variety of configurations of the piston assemblycan be employed to provide a piston assembly with an increased pistonreservoir volume for a given application.

With reference, now, to FIG. 12A, one example of a piston assembly 500configured for use in forming a gas spring and gas damper assembly(e.g., assemblies 102, 102′ and/or 200) in accordance with the subjectmatter of the present disclosure is shown. Piston assembly 500 caninclude a shell 502 having a piston profile portion 504 extending from afirst side of a base plate 506, and can also include a lower reservoirportion 508 in the form of a pair of spaced apart reservoir extensions510 and 512 extending from a second side of base plate 506. Reservoirextensions 510 and 512 together with base plate 506 at least partiallydefine a recess in the form of channel 514. A mounting surface 516 isprovided and includes a threaded bore 518 configured to receive athreaded fastener (not shown) for securing piston assembly 500 to anassociated structural component, such as associated structural memberST2 in FIG. 2, for example, in a similar manner to that previouslydisclosed in connection with FIG. 2. In addition to threaded bore 518or, in the alternative thereto, bores 520 can be provided throughreservoir extensions 510 and 512 for receiving fasteners for furthersecuring piston assembly 500 to an associated structural component(e.g., associated structural member ST2).

Reservoir extensions 510 and 512 are configured to straddle opposingsides of an associated structural component when mounted thereto. Thus,unlike the embodiment of FIGS. 2-7 which is generally mounted to an endof a structural member, piston assembly 500 can be mounted at a middleportion of a structural member (e.g., between respective ends), or at anend thereof depending on the application. As noted, however, a widevariety of configurations of the piston assembly can be employed toprovide a piston assembly with an increased piston reservoir volume fora given application.

Shell 502 can include a side wall (or side wall portion) 522 thatextends from along base plate 506 toward an end wall (or end wallportion) 524 that extends generally transverse to axis AX. It will berecognized that a wide variety of sizes, shapes, profiles and/orconfigurations can and have been used in forming end members of the typeand kind referred to as pistons or roll-off pistons, such as end member500, for example. As such, it will be appreciated that the wall portionsof the end member (e.g., side wall portion 522) can be of any suitableshape, profile and/or configuration, such as may be useful to provideone or more desired performance characteristics, for example, and thatprofile portion 504 shown in FIG. 12A is merely exemplary. Side wallportion 522 has an outer surface 526 that abuttingly engages flexiblesleeve 206 (FIG. 2) such that a rolling lobe 206A (FIG. 2) is formed byflexible sleeve 206 along the outer surface. As a gas spring and gasdamper assembly (e.g., assemblies 102, 102′ and/or 200) in accordancewith the subject matter of the present disclosure is displaced betweencompressed and extended conditions, rolling lobe 206A can be displacedalong outer surface 526 in a generally conventional manner.

As indicated above, it will be appreciated that the one or more endmembers of the gas spring and gas damper assembly can be operativelyconnected or otherwise secured to the flexible spring member in anysuitable manner. For example, shell 502 can include a side wall portion528 that extends longitudinally-outwardly beyond end wall portion 524,and extends peripherally about axis AX. Side wall portion 528 can havean outer surface 530 that is dimensioned to receive lower mounting bead212 (FIG. 2) of flexible sleeve 206 such that a substantiallyfluid-tight seal can be formed therebetween. In some cases, a retainingridge 532 can project radially outward from along the side wall portion528 and can extend peripherally along at least a portion thereof, suchas may assist in retaining lower mounting bead 212 of flexible sleeve206 in abutting engagement on or along the side wall portion.

In some cases, a cover wall (or cover wall portion) 534 can extendacross and thereby form a closed end (not numbered) of end member 500generally opposite reservoir extensions 510 and 512. It will beappreciated that any suitable configuration and/or arrangement of wallsand/or wall portions can be used. As one example, cover wall 534 extendsacross a distal end (not numbered) of side wall portion 528, such as isshown in FIG. 12A, for example. It will be appreciated, however, thatother configurations and/or arrangements could alternately be used.

A gas spring and gas damper assembly in accordance with the subjectmatter of the present disclosure can include or be otherwise associatedwith at least one additional volume, reservoir and/or other chamber thatis dissociated or otherwise fluidically distinguishable from the springchamber. It will be appreciated that any combination of one or morevolumes, reservoirs and/or other chambers that are internal and/orexternal to the gas spring and gas damper assembly can be used. Forexample, in some cases, one or more end members of the gas spring andgas damper assembly can at least partially define the spring chamber andcan also at least partially define an additional volume, reservoir orchamber that is internal to the gas spring and gas damper assembly. Itwill be appreciated, however, that such one or more end members can beof any suitable type, kind, configuration and/or construction.

As one example, end member 500 includes a damper reservoir 536 that isat least partially defined by base plate 506, side wall portion 522, endwall portion 524, side wall portion 528 and/or cover wall portion 534.In a preferred arrangement, one or more openings or ports 538 can extendthrough end wall portion 524 and in fluid communication between springchamber 208 and damper reservoir 536. In such cases, pressurized gas canbe transferred into, out of and between the spring chamber and thedamper reservoir as the gas spring and gas damper assembly is displacedbetween compressed and extended conditions during use. In a preferredarrangement, the size, shape and/or configuration of port 538 can beconfigured such that pressurized gas damping of vibrations at a firstpredetermined frequency or across a first predetermined range offrequencies can be provided as pressurized gas passes into, out of andbetween spring chamber 208 and damper reservoir 536.

Additionally, in some cases, reservoir sections 510 and 512 can also bedisposed in fluid communication with one or more of spring chamber 208and/or damper reservoir 536, such as will be described hereinafter. Forexample, reservoir sections 510 and 512 are configured to straddleopposing sides of an associated structural component when mountedthereto. Reservoir sections 510 and 512 are respectively formed fromreservoir walls (or wall portions) 540 and 542 that at least partiallydefine reservoir extension volumes 544 and 546. It will be appreciated,however, that a wide variety of other configurations and/or arrangementsof the end member sections could alternately be used to provide an endmember with an increased reservoir volume for a given application. Insome cases, end member 500 can include an opening or port 548 in fluidcommunication between damper reservoir 536 and reservoir extensionvolume 542. In such case, pressurized gas can be transferred into, outof and between the spring chamber and reservoir extension volume 544 asthe gas spring and gas damper assembly is displaced between compressedand extended conditions during use. In a preferred arrangement, port 548can be sized to permit damper reservoir 536 and reservoir extensionvolume 542 to act as a substantially contiguous volume.

Additionally, a gas spring and gas damper assembly in accordance withthe subject matter of the present disclosure can include one or moreelongated gas damping passages fluidically connected between the springchamber and one or more additional volumes (e.g., one of damperreservoir 536, reservoir extension 544 and/or 546). Generally, the oneor more elongated gas damping passages can be dimensioned such thatpressurized gas flows into, out of and/or otherwise is displaced withinthe elongated gas damping passage or passages. As a result, suchpressurized gas flow can generate pressurized gas damping of vibrationsand/or other dynamic inputs acting on the overall assembly and/orsystem. In a preferred arrangement, such pressurized gas damping can beconfigured for or otherwise targeted to dissipate vibrations and/orother dynamic inputs having a particular, predetermined naturalfrequency or within a particular, predetermined range of frequencies.

It will be appreciated that the one or more elongated gas dampingpassages can be provided in any suitable manner and through the use ofany suitable combination of one or more features, elements and/orcomponents. For example, a gas spring and gas damper assembly inaccordance with the subject matter of the present disclosure, such as isshown in FIG. 12A, for example, can include an elongated gas dampingpassage 550 that is at least substantially-entirely disposed withindamper reservoir 536, and extends between a passage end 552 disposed influid communication with spring chamber 208 (FIG. 2) and a passage end554 disposed in fluid communication with reservoir extension volume 546.The elongated gas damping passage will have an overall length (notrepresented) and a cross-sectional shape with a maximum cross-sectionaldimension (not identified), such as an approximately circular, ovoid,elliptical, rectangular, square or other curved or polygonal shape, forexample. It will be appreciated that the cross-sectional shape can, insome cases, be substantially uniform along the length of the passage. Inother cases, different sections or portions of the elongated gas dampingpassage could have different cross-sectional shapes.

Additionally, elongated gas damping passage 550 can be formed in anysuitable manner and from any suitable combination of features, elementsand/or components, such as an elongated length of tubular material thatis arranged in or otherwise extends through a plurality of helical coilsor loops. It will be appreciated that any other configuration and/orarrangement could alternately be used, such as annular and/orserpentine, for example. Additionally, the elongated length of tubularmaterial can be formed from any suitable material or combination ofmaterials, such as metal (e.g., aluminum, brass, copper, steel) and/orpolymeric materials (e.g., rigid or flexible thermoplastic material).Furthermore, the elongated length of tubular material can be formed intoor otherwise include a tube wall 556 that at least partially defineselongated gas damping passage 550. The tube wall of passage 550 caninclude a tube end (not identified) that is secured on or along end wallportion 524 through which passage end 552 extends and a tube end (notidentified) that is secured on or along base plate 506 through whichpassage end 554 extends.

Additionally, a gas spring and gas damper assembly in accordance withthe subject matter of the present disclosure can, optionally, includeone or more flow control devices and/or systems that are operativelyconnected between the spring chamber and one or more of the damperreservoir and/or reservoir extensions. For example, one or more controldevice 558 can be disposed in fluid communication between passage end552 and passage end 554. It will be appreciated that any suitable type,kind and/or combination of control devices can be used. If provided,control device 558 can be operative to or otherwise assist in generatingpressurized gas damping of vibrations at a second predeterminedfrequency or across a second predetermined range of frequencies that isdifferent form the first frequency or frequency range.

As indicated above, a gas spring and gas damper assembly in accordancewith the subject matter of the present disclosure can include one ormore elongated gas damping passages fluidically connected between thespring chamber and one or more gas damper reservoirs. In suchconstructions, pressurized gas damping performance exceeding thatprovided by conventional gas damping orifice designs can be achievedthrough the use of such one or more elongated gas damping passages,particularly with respect to a given or otherwise predetermined range offrequencies of vibration or other dynamic input.

Generally, the one or more elongated gas damping passages can bedimensioned such that pressurized gas flows into, out of and/orotherwise is displaced within the elongated gas damping passage orpassages. As a result, such pressurized gas flow can generatepressurized gas damping of vibrations and/or other dynamic inputs actingon the overall assembly and/or system. In a preferred arrangement, suchpressurized gas damping can be configured for or otherwise targeted todissipate vibrations and/or other dynamic inputs having a particular,predetermined natural frequency or within a particular, predeterminerange of frequencies.

As discussed above, a gas spring and gas damper assembly in accordancewith the subject matter of the present disclosure can include anelongated gas damping passage in fluid communication between the springchamber and an associated gas damper reservoir (e.g., one of reservoirsextension volumes 544 and 546). Differential pressure between theassociated chambers (e.g., spring chamber 202 and one of gas reservoirextension volumes 544 and 546) can induce gas flow along at least aportion of the length of the elongated gas damping passage. It will beappreciated that such movement of the pressurized gas within and/orthrough an elongated gas damping passage can act to dissipate kineticenergy acting on the assembly and/or system.

It will be appreciated that the cross-sectional area and overall lengthof the elongated gas damping passage can be dimensioned, sized and/orotherwise configured to generate gas flow having sufficient mass andsufficient velocity to achieve the desired level of pressurized gasdamping. Additionally, in a preferred arrangement, the elongated gasdamping passages can be dimensioned, sized and/or otherwise configuredsuch that one or more performance characteristics, such as peak LossStiffness, for example, of the system occur at approximately a desiredor target frequency or otherwise within a desired or targeted frequencyrange. Non-limiting examples of targeted frequency ranges can includevibrations from 14 Hz, vibrations from 8-12 Hz and vibrations from 15-25Hz.

FIG. 18 a graphical representation of one example of performancecharacteristics of a gas spring and damper assembly that includes anelongated gas damping passage in accordance with the subject matter ofthe present disclosure. More specifically, FIG. 18 is a graphicalrepresentation of stiffness versus frequency and includes a plot linerepresenting pipe storage and a plot line representing pipe loss. Itwill be recognized from FIG. 18 that peak loss stiffness of the pipeloss plot line occurs at approximately 10 Hz or within a range of fromapproximately 8-12 Hz, which can represent a targeted frequency ortargeted range of frequencies for vibration damping.

As discussed above, a gas spring and gas damper assembly in accordancewith the subject matter of the present disclosure can include acombination of features and/or components suitable for generatingpressurized gas damping at two or more predetermined or targetedfrequencies or otherwise within two or more predetermined or otherwisetargeted ranges of frequencies. FIG. 19 a graphical representation ofanother example of performance characteristics of a gas spring anddamper assembly that includes a combination of an elongated gas dampingpassage and a gas damping orifice or port, an additional elongateddamping passage and/or one or more other control devices in accordancewith the subject matter of the present disclosure. More specifically,FIG. 19 is a graphical representation of stiffness versus frequency andincludes a plot line representing pipe storage and a plot linerepresenting pipe loss. It will be recognized from FIG. 19 that twooccurrences of peak loss stiffness of the pipe loss plot line arerepresented. It will be appreciated that the combination of springchamber, gas damping reservoir or reservoirs, elongated gas dampingpassage or passages and/or any additional control devices can generatepressurized gas damping having a peak loss stiffness at approximately2.5 Hz or within a range of from approximately 1-4 Hz and a peak lossstiffness at approximately 9 Hz or within a range of from approximately7-11 Hz, which can represent targeted frequencies or targeted ranges offrequencies for vibration damping.

As discussed above, the combination of cross-sectional area and overalllength of the elongated gas damping passage can be dimensioned, sizedand/or otherwise configured to generate gas flow having sufficient massand sufficient velocity to achieve the desired level of pressurized gasdamping. Generally, a gas spring and gas damper assembly in accordancewith the subject matter of the present disclosure can include anelongated gas damping passage that has an overall length that is atleast (10) times the maximum dimension of the cross-sectional shape(e.g., the diameter of a circular passage) of the elongated gas dampingpassage. In a preferred arrangement, the overall length of the elongatedgas damping passage will be at least twenty (20) times the maximumdimension of the cross-sectional shape. In a more preferred arrangement,the overall length of the elongated gas damping passage will be at leastone hundred (100) times the maximum dimension of the cross-sectionalshape of the elongated gas damping passage. Non-limiting examples ofsuitable ranges for dimensions of an elongated gas damping passage inaccordance with the subject matter of the present disclosure can includean inside cross-sectional dimension (e.g., inside diameter) within arange of from approximately five (5) millimeters to approximately fifty(50) millimeters and an overall length of from approximately one-half(0.5) meter to approximately five (5) meters.

As shown herein, the one or more elongated gas damping passages aretypically disposed within the associated gas spring and gas damperassembly. In some cases, substantially all of the elongated gas dampingpassages can be provided outside of the spring chamber (e.g., springchamber 208), such as by extending within or through one of the endmembers (e.g., end member 500). Though not specifically shown in use inconnection with the remaining end members (e.g., end members 204, 404and/or 604), it will be appreciated that the application and use of oneor more elongated gas damping passages is equally applicable to endmembers 204, 404 and 604, without limitation.

As described above, it will be appreciated that the one or moreelongated gas damping passages can be configured or otherwise arrangedwithin the gas spring and gas damper assembly in any suitable manner,such as by having one or more portions or sections that are linear,coiled, curved, serpentine or any combination of these and/or otherconfigurations and/or arrangements. In some cases, performance benefitsmay be achieved by using a coiled or helical arrangement in comparisonwith other configurations. In such cases, it will be appreciated thatany suitable coil dimension can be used, such as an outside diameterwithin a range of from approximately twenty (20) millimeters toapproximately five hundred (500) millimeters, for example.

It will be appreciated that the one or more elongated gas dampingpassages can provided in any suitable manner and through the use of anysuitable combination of one or more features, elements and/orcomponents. For example, one or more elongated gas damping passages canbe at least partially formed by one or more components that are providedseparately from the one or more walls and/or wall portions of the endmembers. As another example, one or more elongated gas damping passagescan be at least partially formed by one or more walls and/or wallportions of one or more of the end members.

Turning to FIGS. 13-17, yet another exemplary configuration of a pistonassembly is illustrated that is suitable for forming a gas springassembly in accordance with the subject matter of the presentdisclosure, such as one or more of gas spring assemblies 102 and/or 102′in FIG. 1, for example. In this embodiment, piston assembly 604 issimilar in most respects to piston assembly 404 of FIGS. 9-12, and likereference numerals denote common features of each embodiment. Pistonassembly 604 differs from piston assembly 404 in that the reservoirportion is in the form of a single auxiliary reservoir extension 652.Thus, rather than straddling an associated structural component, such asassociated structural member ST2 in FIG. 2, for example, piston assembly604 is adapted to be mounted along a first surface of the associatedstructural member with reservoir extension 652 disposed on or along anadjacent side or surface of the associated structural member.

It will now be appreciated that embodiments of the present disclosureprovide a gas spring assembly having a piston assembly with an increasedpiston chamber volume as compared to prior art gas spring assemblies.Such increased volume is achieved at least in part by locating a portionof the piston chamber volume on an opposing side of a mounting surfacefrom the piston profile portion of the piston assembly, such as below amounting surface of the piston assembly in void space, for example, thatis on, along or otherwise adjacent to a structural member to which thepiston assembly is to be mounted. As such, a wide variety of shellshapes are envisioned to accommodate a wide variety of applications. Aswill be appreciated, the void space available adjacent a structuralmember of a given vehicle will vary from vehicle to vehicle. Thus,aspects of the invention are relevant to designing a piston assembly toutilize such unused space for increasing the volume of the pistonchamber. For example, a method of making a gas spring in accordance withthe exemplary embodiments of the invention could include detecting voidspace adjacent a support member of a vehicle, and constructing a pistonassembly having a piston chamber adapted to occupy a portion of thedetected void space.

It will be appreciated that the gas spring assemblies of the presentdisclosure can be operatively connected between the sprung and unsprungmasses of an associated vehicle in any suitable manner. For example, asshown in FIG. 1 the gas spring assemblies can be operatively connectedbetween wheel-engaging members and a body of a vehicle VHC. It will beappreciated, however, that the configuration of vehicle VHC in FIG. 1 ismerely a schematic representation of the structural components of thesprung and unsprung masses of the vehicle. Thus, it will be understoodthat this schematic representation is provided for purposes ofdiscussion and ease of understanding and is not intended to be in anyway limiting.

As used herein with reference to certain features, elements, componentsand/or structures, numerical ordinals (e.g., first, second, third,fourth, etc.) may be used to denote different singles of a plurality orotherwise identify certain features, elements, components and/orstructures, and do not imply any order or sequence unless specificallydefined by the claim language. Additionally, the terms “transverse,” andthe like, are to be broadly interpreted. As such, the terms“transverse,” and the like, can include a wide range of relative angularorientations that include, but are not limited to, an approximatelyperpendicular angular orientation. Also, the terms “circumferential,”“circumferentially,” and the like, are to be broadly interpreted and caninclude, but are not limited to circular shapes and/or configurations.In this regard, the terms “circumferential,” “circumferentially,” andthe like, can be synonymous with terms such as “peripheral,”“peripherally,” and the like.

Furthermore, the phrase “flowed-material joint” and the like, if usedherein, are to be interpreted to include any joint or connection inwhich a liquid or otherwise flowable material (e.g., a melted metal orcombination of melted metals) is deposited or otherwise presentedbetween adjacent component parts and operative to form a fixed andsubstantially fluid-tight connection therebetween. Examples of processesthat can be used to form such a flowed-material joint include, withoutlimitation, welding processes, brazing processes and solderingprocesses. In such cases, one or more metal materials and/or alloys canbe used to form such a flowed-material joint, in addition to anymaterial from the component parts themselves. Another example of aprocess that can be used to form a flowed-material joint includesapplying, depositing or otherwise presenting an adhesive betweenadjacent component parts that is operative to form a fixed andsubstantially fluid-tight connection therebetween. In such case, it willbe appreciated that any suitable adhesive material or combination ofmaterials can be used, such as one-part and/or two-part epoxies, forexample.

Further still, the term “gas” is used herein to broadly refer to anygaseous or vaporous fluid. Most commonly, air is used as the workingmedium of gas spring devices, such as those described herein, as well assuspension systems and other components thereof. However, it will beunderstood that any suitable gaseous fluid could alternately be used.

It will be recognized that numerous different features and/or componentsare presented in the embodiments shown and described herein, and that noone embodiment may be specifically shown and described as including allsuch features and components. As such, it is to be understood that thesubject matter of the present disclosure is intended to encompass anyand all combinations of the different features and components that areshown and described herein, and, without limitation, that any suitablearrangement of features and components, in any combination, can be used.Thus it is to be distinctly understood claims directed to any suchcombination of features and/or components, whether or not specificallyembodied herein, are intended to find support in the present disclosure.

Thus, while the subject matter of the present disclosure has beendescribed with reference to the foregoing embodiments and considerableemphasis has been placed herein on the structures and structuralinterrelationships between the component parts of the embodimentsdisclosed, it will be appreciated that other embodiments can be made andthat many changes can be made in the embodiments illustrated anddescribed without departing from the principles hereof. Obviously,modifications and alterations will occur to others upon reading andunderstanding the preceding detailed description. Accordingly, it is tobe distinctly understood that the foregoing descriptive matter is to beinterpreted merely as illustrative of the subject matter of the presentdisclosure and not as a limitation. As such, it is intended that thesubject matter of the present disclosure be construed as including allsuch modifications and alterations insofar as they come within the scopeof the appended claims and any equivalents thereof.

1. A gas spring and gas damper assembly comprising: an end memberadapted to be mounted along a first associated support structure; apiston assembly adapted to be mounted along a second associated supportstructure spaced from the first associated support structure; and, aflexible sleeve extending between and sealingly connected to said endmember and said piston assembly, and forming a main chamber therebetweenfor containing a pressurized gas; said piston assembly including: ashell including a piston profile portion thereof having an exteriorsurface over which said flexible sleeve is configured to roll, saidshell generally defining a piston chamber for containing a pressurizedgas; a mounting surface dimensioned to mount said piston assembly alongthe second associated support structure, said mounting surface at leastpartially defining a mounting plane and being recessed into said shellsuch that said piston chamber extends through said mounting plane suchthat said piston chamber at least partially surrounds the secondassociated support structure on at least two sides when said pistonassembly is mounted along the second associated support structure; and,a gas damping passage disposed in fluid communication between said mainchamber and said piston chamber such that, upon displacement of said gasspring and gas damper assembly between extended and compressedconditions, pressurized gas transferred through said gas damping passagedissipates kinetic energy acting on said gas spring and gas damperassembly.
 2. A gas spring assembly as set forth in claim 1, wherein saidshell includes a generally cylindrical upper portion and a generallytoroidal-shaped lower portion.
 3. A gas spring assembly as set forth inclaim 2, wherein said mounting surface is recessed into saidtoroidal-shaped lower portion of said piston chamber.
 4. A gas springassembly as set forth in claim 2, wherein said toroidal-shaped lowerportion is configured to surround said mounting surface such that saidpiston chamber at least partially surrounds the second associatedsupport structure on at least four sides thereof when said pistonassembly is mounted along the second associated support structure.
 5. Agas spring assembly as set forth in claim 1, wherein said piston chamberincludes an upper chamber portion and a lower reservoir extension, saidlower reservoir extension configured to extend parallel to an associatedlinear edge of the second associated mounting member.
 6. A gas springassembly as set forth in claim 1, wherein said recessed mounting surfaceis located in a U-shape recess in said shell.
 7. A vehicle suspensionsystem comprising: a first support structure; a second supportstructure; and, a gas spring assembly as set forth in claim 1 mounted tosaid first and second support structures.
 8. A gas spring and gas damperassembly comprising: an end member adapted to be mounted to a firstassociated support structure; a piston assembly adapted to be mounted toa second associated support structure spaced from the first associatedsupport structure; and, a flexible sleeve extending between andsealingly connected to said end member and said piston assembly, andforming a main chamber therebetween for containing a pressurized gas;said piston assembly including: a shell including a shell wall with apiston profile portion and a reservoir portion, said piston portionhaving an exterior surface over which said flexible sleeve is configuredto roll with at least said piston profile portion of said shell wallgenerally defining a piston chamber in fluid communication with saidmain chamber and for containing the pressurized gas, and said reservoirportion rigidly interconnected in fluid communication with said pistonchamber for containing the pressurized gas; a mounting surface formounting said piston assembly to the second associated support, saidmounting surface being recessed into said shell and defining a mountingplane, said piston profile portion extending in a first direction fromsaid mounting plane and said reservoir portion extending in a seconddirection from said mounting plane; and, a gas damping passage disposedin fluid communication between said main chamber and at least one ofsaid piston chamber and said reservoir portion such that, upondisplacement of said gas spring and gas damper assembly between extendedand compressed conditions, pressurized gas transferred through said gasdamping passage dissipates kinetic energy acting on said gas spring andgas damper assembly said piston assembly dimensioned to be mounted tothe associated second support structure such that said piston profileportion can be located on a first side of the second associated supportstructure and said piston reservoir portion can be located on a secondside of the second associated support structure.
 9. A gas springassembly as set forth in claim 8, wherein said piston assembly has aside elevation view and said reservoir portion of said shell wallincludes a cross-sectional profile from along said side elevation viewthat includes a shell wall portion having a generally U-shapedconfiguration with opposing side wall portions and a bottom wall portionextending between said side wall portions, said bottom wall portionincluding said mounting surface such that, when mounted to the secondassociated support structure, said piston reservoir straddles the secondassociated support structure.
 10. A gas spring assembly as set forth inclaim 8, wherein said reservoir portion has a shape corresponding tosaid shape of the second associated support structure such that whenmounted to the second associated support structure, said reservoirsurrounds the second associated support structure on at least two sides.11. A gas spring assembly as set forth in claim 8, wherein said shellincludes a generally cylindrical upper portion, and wherein saidreservoir portion is generally toroidal shape.
 12. A gas spring assemblyas set forth in claim 8, wherein said mounting surface is recessed intosaid reservoir portion.
 13. A gas spring assembly as set forth in claim8, wherein said reservoir portion is configured to surround an end ofthe second associated support structure such that, when mounted to thesecond associated support structure, said piston chamber at leastpartially surrounds the second associated support structure on at leastfour sides thereof.
 14. A gas spring assembly as set forth in claim 8,wherein said piston chamber includes a generally cylindrical upperportion, and said reservoir portion is configured to extend parallel toa linear edge of the second associated support structure.
 15. A gasspring assembly as set forth in claim 8, wherein said mounting surfaceis located in a U-shape recess in said shell.
 16. A vehicle suspensionsystem comprising: a first support member; a second support member; and,a gas spring assembly as set forth in claim 8 mounted to said first andsecond support members.
 17. A piston assembly for a gas spring, saidpiston assembly comprising: a shell including a shell wall with a pistonprofile portion thereof having an exterior surface over which anassociated flexible sleeve can be configured to roll, said shell wallgenerally defining a piston chamber for containing a pressurized fluid;a mounting surface for mounting said piston assembly to an associatedsupport member, said mounting surface being recessed into said shellsuch that said piston chamber extends through a mounting plane of saidpiston defined by said mounting surface; and, a gas damping passageextending through said shell wall of said shell and disposed in fluidcommunication with said piston chamber, said gas damping passagedimensioned such that pressurized gas transferred through said gasdamping passage can dissipate kinetic energy acting on said pistonassembly; said piston assembly dimensioned to be mounted to theassociated support member such that said piston chamber at leastpartially surrounds the associated support member on at least two sidesthereof.
 18. A piston assembly as set forth in claim 17, wherein saidshell includes a generally cylindrical upper portion, and a generallytoroidal lower portion.
 19. A piston assembly as set forth in claim 18,wherein said recessed mounting surface is recessed into said toroidallower portion of said piston chamber.
 20. A piston assembly as set forthin claim 18, wherein said toroidal lower portion is configured tosurround an end of said second mounting surface such that, when mountedto the associated support member, said piston chamber at least partiallysurrounds the associated support member on at least four sides thereof.